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    <title>Image Read and Write Functions</title>
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    <div class="refentry">
      <a id="id-1"></a>
      <div class="titlepage"></div>
      <div xmlns="" class="refnamediv">
        <h1>Image Read and Write Functions</h1>
        <p>Click an item in the table below for details about that function.</p>
      </div>
      <div class="refsect1">
        <a id="springboard"></a>
        <h2></h2>
        <div class="informaltable">
          <table border="1">
            <colgroup>
              <col align="left" class="col1" />
              <col align="left" class="col2" />
            </colgroup>
            <tbody>
              <tr>
                <td align="left"><a class="citerefentry" href="read_imagef2d.html"><span class="citerefentry"><span class="refentrytitle">read_imagef</span></span></a> for 2D</td>
                <td align="left">Do an element lookup in the 2D image object, returning floating-point values</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="read_imagei2d.html"><span class="citerefentry"><span class="refentrytitle">read_image{i|ui}</span></span></a> for 2D</td>
                <td align="left">Do an element lookup in the 2D image object, returning unnormalized signed integer and unsigned integer values</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="read_imageh2d.html"><span class="citerefentry"><span class="refentrytitle">read_imageh</span></span></a> for 2D</td>
                <td align="left">OPTIONAL function to do an element lookup in the 2D image object, returning floating-point values. Enabled with <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>.</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="write_image.html"><span class="citerefentry"><span class="refentrytitle">write_image {f|i|ui}</span></span></a>  or 2D</td>
                <td align="left">Write <code class="varname">color</code> value to location in the 2D image object</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="write_imageh2d.html"><span class="citerefentry"><span class="refentrytitle">write_imageh</span></span></a> for 2D</td>
                <td align="left">OPTIONAL function to write <code class="varname">color</code> value in a 3D object. Enabled with <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>.</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="read_imagef3d.html"><span class="citerefentry"><span class="refentrytitle">read_imagef</span></span></a> for 3D</td>
                <td align="left">Do an element lookup in the 3D image object, returning floating-point values</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="read_imagei3d.html"><span class="citerefentry"><span class="refentrytitle">read_imagei</span></span></a> for 3D</td>
                <td align="left">Do an element lookup in the 3D image object, returning unnormalized signed integer and unsigned integer values</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="read_imageh3d.html"><span class="citerefentry"><span class="refentrytitle">read_imageh</span></span></a> for 3D</td>
                <td align="left">Do an element lookup in the 3D image object, returning half floating point values. Enabled with <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>.</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="write_imageh3d.html"><span class="citerefentry"><span class="refentrytitle">write_imageh</span></span></a> for 3D</td>
                <td align="left">OPTIONAL function to write <code class="varname">color</code> value in a 3D object. Enabled with <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a>.</td>
              </tr>
              <tr>
                <td align="left"><a class="citerefentry" href="cl_khr_3d_image_writes.html"><span class="citerefentry"><span class="refentrytitle">write_image{f i ui}</span></span></a> for 3D</td>
                <td align="left">OPTIONAL function to write <code class="varname">color</code> value in a 3D object. Enabled with <a class="citerefentry" href="cl_khr_3d_image_writes.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_3d_image_writes</span></span></a>.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="get_image_width.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">get_image_width</span>
                    </span>
                  </a>
                </td>
                <td align="left">Return the image width in pixels</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="get_image_height.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">get_image_height</span>
                    </span>
                  </a>
                </td>
                <td align="left">Return the image height in pixels.</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="get_image_depth.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">get_image_depth</span>
                    </span>
                  </a>
                </td>
                <td align="left">Return the 3D image depth in pixels</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="get_image_channel_data_type.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">get_image_channel_data_type</span>
                    </span>
                  </a>
                </td>
                <td align="left">Return the image channel data type</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="get_image_channel_order.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">get_image_channel_order</span>
                    </span>
                  </a>
                </td>
                <td align="left">Return the image channel order</td>
              </tr>
              <tr>
                <td align="left">
                  <a class="citerefentry" href="get_image_dim.html">
                    <span class="citerefentry">
                      <span class="refentrytitle">get_image_dim</span>
                    </span>
                  </a>
                </td>
                <td align="left">Return the image dimensions</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
            The built-in image function calls to read and write images are supported. 
        </p>
        <p>
The image read and write functions are extended with <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a> to include appropriate versions of functions that take <span class="type">half4</span> as arguments and return values. 
        </p>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>  
        The built-in functions defined in this section can only be used with image memory objects
created with <a class="citerefentry" href="clCreateImage2D.html"><span class="citerefentry"><span class="refentrytitle">clCreateImage2D</span></span></a>, or <a class="citerefentry" href="clCreateImage3D.html"><span class="citerefentry"><span class="refentrytitle">clCreateImage3D</span></span></a>. An image memory object can be
accessed by specific function calls that read from and/or write to specific locations in the image.
        </p>
        <p>
Image memory objects that are being read by a kernel should be declared with the
<a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">__read_only</span></span></a> qualifier. <a class="citerefentry" href="write_image.html"><span class="citerefentry"><span class="refentrytitle">write_image</span></span></a> calls to image memory objects declared with the
<a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">__read_only</span></span></a> qualifier will generate a compilation error. Image memory objects that are
being written to by a kernel should be declared with the <a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">__write_only</span></span></a> qualifier.
<a class="citerefentry" href="read_image.html"><span class="citerefentry"><span class="refentrytitle">read_image</span></span></a> calls to image memory objects declared with the <a class="citerefentry" href="accessQualifiers.html"><span class="citerefentry"><span class="refentrytitle">__write_only</span></span></a> qualifier will
generate a compilation error. <a class="citerefentry" href="read_image.html"><span class="citerefentry"><span class="refentrytitle">read_image</span></span></a> 
and <a class="citerefentry" href="write_image.html"><span class="citerefentry"><span class="refentrytitle">write_image</span></span></a> calls to the same image memory
object in a kernel are not supported.
        </p>
        <p>
The <a class="citerefentry" href="read_image.html"><span class="citerefentry"><span class="refentrytitle">read_image</span></span></a> calls returns a four component floating-point, integer or unsigned integer color
value. The color values returned by <a class="citerefentry" href="read_image.html"><span class="citerefentry"><span class="refentrytitle">read_image</span></span></a> are identified as <em class="replaceable"><code>x, y, z, w</code></em> where <em class="replaceable"><code>x</code></em> refers to
the red component, <em class="replaceable"><code>y</code></em> refers to the green component, <em class="replaceable"><code>z</code></em> refers to the blue component and <em class="replaceable"><code>w</code></em> refers to the alpha component.
        </p>
        <p>
        The image read functions take a sampler argument. The sampler can be passed as an argument
to the kernel using <a class="citerefentry" href="clSetKernelArg.html"><span class="citerefentry"><span class="refentrytitle">clSetKernelArg</span></span></a>, or it can be a constant variable of type <a class="citerefentry" href="sampler_t.html"><span class="citerefentry"><span class="refentrytitle">sampler_t</span></span></a> declared in the program source.
        </p>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />
                                                 
            <a href="http://www.khronos.org/registry/cl/specs/opencl-1.1.pdf#page=234" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="sampler_t.html"><span class="citerefentry"><span class="refentrytitle">sampler_t</span></span></a>, <a class="citerefentry" href="cl_khr_3d_image_writes.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_3d_image_writes</span></span></a>
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2010 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
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